A projection display that is called a short focus (ultra-short focus) projector makes it possible to project and display a picture of a wide visual field and high definition from a very short projection distance. Such a projection display prevents the shadow or the like of a user approaching a projection surface from being displayed on the projection surface, and also makes it possible to display a picture with realistic sensation. For example, the projection display makes it possible to project an image of a wide visual field on the wall surface of a lounge, etc. The projection display has attracted attention as new picture displaying technology available in a daily space.
On the other hand, such a projection display projects pictures at a shallow angle to the projection surface, and thus causes the distortion (deformation) of a projection image due to slight displacements (for example, unevenness, asperities, steps) on the projection surface. For example, a completely flat wall surface is impractical for a common residence for structural reasons. There is a demand for functions which make it possible to correct the distortion of projection image and make the distortion less conspicuous when an uneven projection surface serves as the projection surface, for example.
To meet the demand, a scheme is proposed which involves projecting a pattern image for calibration of a distortion, capturing an image of the projected pattern image with a camera prepared separately, calculating a distortion on the basis of the captured image to correct the projection image (for example, PTL 1). Another technology that corrects a projection image involves capturing an image of a pattern image with a camera mounted on the body of a projection display, and performing shape correction (keystone correction) on the projected screen on the basis of the captured image (PTL 2), etc.